Heat exchanger tube

ABSTRACT

In a heat exchanger tube, a brazing material, which is required for brazing tops ( 310 ) of inner fins ( 300 ) which are a flow passage dividing body and the inner surface of a tube body portion ( 200 ), not clad to a first material which constitutes the tube body portion but clad to a second material which constitutes the inner fins. In the heat exchanger tube, the tube has a thickness t tube  of 1.2 mm or less and a width W tube  of 16 mm or less, the first material has a thickness t 1  of 0.25 mm or less, the second material has a thickness t 2  of 0.10 mm or less, and the flow passages divided by the inner fins have an equivalent diameter of 0.559 mm or less. Besides, when brazing in a furnace, a brazing material disposed within the flow passages melts earlier than a brazing material which penetrates from outside into the flow passages, thereby preventing the flow passages from being clogged.

TECHNICAL FIELD

The present invention relates to heat exchanger tubes in which a mediumflowing through their passages conducts heat exchange with heatconducted to the tubes.

BACKGROUND ART

A heat exchanger such as a radiator, an evaporator or the like used fora refrigerating cycle is known that it is configured by alternatelystacking flat heat exchanger tubes and corrugated radiating fins to forma core and connecting ends of the tubes to tanks. A refrigerant is takeninto the heat exchanger from one of the tanks, flowed through the heatexchanger tubes while performing heat exchange with heat conducted tothe core, and discharged out of the other of the tanks. Such a heatexchanger is produced by assembling the component members such as heatexchanger tubes, fins, tanks and the like into one body and brazing theassembled body in a furnace.

The heat exchanger tubes of the heat exchanger of the above type arealso disclosed in the following Patent Documents 1 through 33. The heatexchanger tubes have the corrugated inner fins disposed within the tubebody portion which configures the outer shell of the flow passages wherethe medium flows, so that the heat exchange efficiency of the medium canbe improved. And, it is possible to improve the compression strength ofthe tubes by brazing the inner fins to the inner surface of the tubebody portion.

-   Patent Document 1: Japanese Patent Laid-Open Publication No. Sho    60-114698-   Patent Document 2: Japanese Utility Model Laid-Open Publication No.    Sho 61 8783-   Patent Document 3: Japanese Patent Laid-Open Publication No. Sho    61-66091-   Patent Document 4: Japanese Utility Model Laid-Open Publication No.    Sho 62-8576-   Patent Document 5: Japanese Utility Model Laid-Open Publication No.    Sho 62 142440-   Patent Document 6: Japanese Utility Model Laid-Open Publication No.    Sho 63 134273-   Patent Document 7: Japanese Utility Model Laid-Open Publication No.    Sho 63 150721-   Patent Document 8: Japanese Utility Model Laid-Open Publication No.    Sho 63 159667-   Patent Document 9: Japanese Utility Model Laid-Open Publication No.    Sho 63-179472-   Patent Document 10: Japanese Utility Model Laid-Open Publication No.    Hei 1-8071-   Patent Document 11: Japanese Patent Laid-Open Publication No.    4-198692-   Patent Document 12: Japanese Patent Laid-Open Publication No. Hei    5-1893-   Patent Document 13: Japanese Patent Laid-Open Publication No. Hei    5-113297-   Patent Document 14: Japanese Patent Laid-Open Publication No. Hei 5    169246-   Patent Document 15: Japanese Patent Laid-Open Publication No. Hei    6-74607-   Patent Document i6: Japanese Patent Laid-Open Publication No. Hei    6-129734-   Patent Document 17: Japanese Patent Laid-Open Publication No. Hei    7-32133-   Patent Document 18: Japanese Patent Laid-Open Publication No. Hei    7-265985-   Patent Document 19: Japanese Patent Laid-Open Publication No. Hei 8    170888-   Patent Document 20: Japanese Patent Laid-Open Publication No. Hei 8    271167-   Patent Document 21: Japanese Patent Laid-Open Publication No. Hei 9    206980-   Patent Document 22: Japanese Patent Laid-Open Publication No. Hei 10    197180-   Patent Document 23: Japanese Patent Laid-Open Publication No. Hei    10-300382-   Patent Document 24: Japanese Patent Laid-Open Publication No. Hei 11    101586-   Patent Document 25: Japanese Patent Laid-Open Publication No. Hei    11-248383-   Patent Document 26: Japanese Patent Laid-Open Publication No. Hei    11-257886-   Patent Document 27: Japanese Patent Laid-Open Publication No. Hei 11    264675-   Patent Document 28: Japanese Patent Laid-Open Publication No.    2000-97589-   Patent Document 29: Japanese Patent Laid-Open Publication No. 2000    105089-   Patent Document 30: Japanese Patent Laid-Open Publication No.    2001-38439-   Patent Document 31: Japanese Patent Laid-Open Publication No. 2001    107082-   Patent Document 32: Japanese Patent Laid-Open Publication No. 2001    221588-   Patent Document 33: Japanese Patent Laid-Open Publication No.    2002-350083

In recent years, the heat exchanger tubes tend to be made compact andprecise in order to improve the performance of the heat exchanger. Toimprove the performance and the productivity, setting of sizes ofindividual components, arrangement of a brazing material and the likeare becoming more and more significant conditions.

The present invention has been made in view of the above circumstancesand an object of the invention is to provide heat exchanger tubes whichare configured more reasonably based on the current productiontechnology.

DISCLOSURE OF THE INVENTION

The invention recited in claim 1 of the present application is a heatexchanger tube comprising: a tube body portion constituting an outershell of flow passages for flowing a medium, and corrugated inner finsfor dividing the flow passages, wherein tops of the inner fins are flattubes brazed to the inner surface of the tube body portion and in whichthe medium performs heat exchange with heat conducted to the tubes,wherein a brazing material which is required for brazing the tops of theinner fins and the inner surface of the tube body portion is not clad toa first material constituting the tube body portion but clad to a secondmaterial constituting the inner fins.

The invention recited in claim 2 of the present application is the heatexchanger tube according to claim 1, wherein a thickness of a clad layerof the brazing material in the second material is 5 to 10% in ratio withrespect to the thickness of the second material.

The invention recited in claim 3 of the present application is the heatexchanger tube according to claim 1 or 2, wherein the second materialhas a thickness of 0.1 mm or less.

The invention recited in claim 4 of the present application is the heatexchanger tube according to claim 3, wherein the second material has athickness of 0.05 to 0.07 mm.

The invention recited in claim 5 of the present application is the heatexchanger tube according to any one of claims 1 through 4, wherein thefirst material has a thickness of 0.25 mm or less.

The invention recited in claim 6 of the present application is the heatexchanger tube according to claim 5, wherein the first material has athickness of 0.18 to 0.24 mm.

The invention recited in claim 7 of the present application is the heatexchanger tube according to any one of claims 1 through 6, wherein thetube has a thickness of 1.2 mm or less.

The invention recited in claim 8 of the present application is the heatexchanger tube according to claim 7, wherein the tube has a thickness of0.8 to 1.2 mm.

The invention recited in claim 9 of the present application is the heatexchanger tube according to any one of claims 1 through 8, wherein thetube has a width of 16 mm or less.

The invention recited in claim 10 of the present application is the heatexchanger tube according to claim 9, wherein the tube has a width of 12to 16 mm.

The invention recited in claim 11 of the present application is the heatexchanger tube according to any one of claims 1 through 10, wherein theflow passages divided by the inner fins have an equivalent diameter of0.559 mm or less.

The invention recited in claim 12 of the present application is the heatexchanger tube according to claim 11, wherein the flow passages dividedby the inner fins have an equivalent diameter of 0.254 mm to 0.559 mm.

The invention recited in claim 13 of the present application is the heatexchanger tube according to any one of claims 1 through 12, wherein thetops of the inner fins have a pitch of 1.0 mm or less.

The invention recited in claim 14 of the present application is the heatexchanger tube according to any one of claims 1 through 13, wherein anAl—Zn alloy layer is formed on the surface of the first material whichbecomes an outer shell of the tube.

The invention recited in claim 15 of the present application is the heatexchanger tube according to any one of claims 1 through 14, wherein thetops of the inner fins are flat.

The invention recited in claim 16 of the present application is the heatexchanger tube according to any one of claims 1 through 15, wherein endsof the second material in its breadth direction are brazed with thefirst material by the brazing material which is clad to the secondmaterial.

The invention recited in claim 17 of the present application is the heatexchanger tube according to claim 16, wherein both ends of the firstmaterial in its breadth direction are engaged and brazed with an end ofthe second material in its breadth direction sandwiched at one end ofthe tube in its breadth direction so as not to separate from each other.

The invention recited in claim 18 of the present application is the heatexchanger tube according to any one of claims 1 through 17, wherein theportion between the tops of the inner fins is not perpendicular withrespect to the central axis of the tube in its breadth direction.

The invention recited in claim 19 of the present application is the heatexchanger tube according to any one of claims 1 through 18, wherein thetube is a constituting member of the heat exchanger, and the heatexchanger is produced by assembling the tubes and other constitutingmembers into one body and brazing the assembled body in a furnace, andthe brazing material clad to the second material melts when brazed inthe furnace earlier than the brazing material which melts from the otherconstituting members and penetrates into the flow passages thereby toprevent the flow passages from being clogged.

The invention recited in claim 20 of the present application is the heatexchanger tube according to claim 19, wherein the brazing material cladto the second material has a melting point lower than that of thebrazing material which melts from the other constituting members andpenetrates into the flow passages.

The invention recited in claim 21 of the present application is the heatexchanger tube according to claim 19, wherein the brazing material cladto the second material melts earlier than the brazing material whichmelts from the other constituting members and penetrates into the flowpassages because the tube has a thermal resistance lower than that ofthe other constituting members.

The invention recited in claim 22 of the present application is the heatexchanger tube according to any one of claims 19 through 21, whereinamong plural flow passages divided by the inner fins, an equivalentdiameter of the flow passage, which is positioned at the lowest positionwhen brazing in the furnace, or individual equivalent diameters of theflow passage positioned at the lowest position and flow passagespositioned nearby when brazing in the furnace are larger than a wholeaverage of the equivalent diameters of the plural flow passages dividedby the inner fins.

The invention recited in claim 23 of the present application is a heatexchanger tube comprising: a tube body portion constituting an outershell of flow passages for flowing a medium, and corrugated inner finsfor dividing the flow passages, wherein the tops of the inner fins areflat tube brazed to the inner surface of the tube body portion and inwhich the medium performs heat exchange with heat conducted to the tube,wherein the tube has a thickness of 1.2 mm or less, the tube has a widthof 16 mm or less, a first material constituting the tube body portionhas a thickness of 0.25 mm or less, a second material constituting theinner fins has a thickness of 0.10 mm or less, and the flow passagesdivided by the inner fins have an equivalent diameter of 0.559 mm orless.

The invention recited in claim 24 of the present application is the heatexchanger tube according to claim 23, wherein the second material has athickness of 0.05 to 0.07 mm.

The invention recited in claim 25 of the present application is the heatexchanger tube according to claim 23 or 24, wherein the first materialhas a thickness of 0.18 to 0.24 mm.

The invention recited in claim 26 of the present application is the heatexchanger tube according to any one of claims 23 through 25, wherein thetube has a thickness of 0.8 to 1.2 mm.

The invention recited in claim 27 of the present application is the heatexchanger tube according to any one of claims 23 through 26, wherein thetube has a width of 12 to 16 mm.

The invention recited in claim 28 of the present application is the heatexchanger tube according to any one of claims 23 through 27, wherein theflow passages divided by the inner fins have an equivalent diameter of0.254 mm to 0.559 mm.

The invention recited in claim 29 of the present application is the heatexchanger tube according to any one of claims 23 through 28, wherein thetops of the inner fins have a pitch of 1.0 mm or less.

The invention recited in claim 30 of the present application is the heatexchanger tube according to any one of claims 23 through 29, wherein anAl-Zn alloy layer is formed on the surface of the first material whichbecomes an outer shell of the tube.

The invention recited in claim 31 of the present application is the heatexchanger tube according to any one of claims 23 through 30, wherein thetops of the inner fins are flat.

The invention recited in claim 32 of the present application is the heatexchanger tube according to any one of claims 23 through 31, whereinends of the second material in its breadth direction are brazed to thefirst material.

The invention recited in claim 33 of the present application is the heatexchanger tube according to claim 32, wherein both ends of the firstmaterial in its breadth direction are engaged and brazed with an end ofthe second material in its breadth direction sandwiched at one end ofthe tube in its breadth direction so as not to separate from each other.

The invention recited in claim 34 of the present application is the heatexchanger tube according to any one of claims 23 through 33, wherein theportion between the tops of the inner fins is not perpendicular withrespect to the central axis of the tube in its breadth direction.

The invention recited in claim 35 of the present application is the heatexchanger tube according to any one of claims 23 through 34, wherein thetube is a constituting member of the heat exchanger, and the heatexchanger is produced by assembling the tubes and other constitutingmembers into one body and brazing the assembled body in a furnace, thebrazing material which is required for brazing the tops of the innerfins and the inner surface of the tube body portion is disposed withinthe flow passages, and the brazing material disposed within the flowpassages melts when brazed in the furnace earlier than the brazingmaterial which melts from the other constituting members and penetratesinto the flow passages thereby to prevent the flow passages from beingclogged.

The invention recited in claim 36 of the present application is the heatexchanger tube according to claim 35, wherein the brazing materialdisposed within the flow passages has a melting point lower than that ofthe brazing material which melts from the other constituting members andpenetrates into the flow passages.

The invention recited in claim 37 of the present application is the heatexchanger tube according to claim 35, wherein the brazing materialdisposed within the flow passages melts earlier than the brazingmaterial which melts from the other constituting members and penetratesinto the flow passages because the tube has a thermal resistance whichis lower than that of the other constituting members.

The invention recited in claim 38 of the present application is the heatexchanger tube according to any one of claims 35 through 37, whereinamong plural flow passages divided by the inner fins, an equivalentdiameter of the flow passage, which is positioned at the lowest positionwhen brazing in the furnace, or individual equivalent diameters of theflow passages positioned at the lowest position and flow passagespositioned nearby when brazing in the furnace are larger than a wholeaverage of the equivalent diameters of the plural flow passages dividedby the inner fins.

The invention recited in claim 39 of the present application is a heatexchanger tube comprising: a tube body portion constituting an outershell of flow passages for flowing a medium, and a flow passage dividingbody for dividing the flow passages the flow passage dividing body beinga tube brazed to the inner surface of the tube body portion, and themedium performing heat exchange with heat conducted to the tube, whereinthe tube is a constituting member of a heat exchanger, and the heatexchanger is produced by assembling the tube and other constitutingmembers into one body and brazing the assembled body in a furnace, abrazing material which is required for brazing the flow passage dividingbody and the inner surface of the tube body portion is disposed withinthe flow passages, and the brazing material disposed within the flowpassages melts when brazed in the furnace earlier than the brazingmaterial which melts from the other constituting members and penetratesinto the flow passages thereby to prevent the flow passages from beingclogged.

The invention recited in claim 40 of the present application is the heatexchanger tube according to claim 39, wherein the flow passage dividingbody is a corrugated inner fins, and the tops of the inner fins arebrazed to the inner surface of the tube body portion.

The invention recited in claim 41 of the present application is the heatexchanger tube according to claim 39, wherein the flow passage dividingbody is beads obtained by shaping a material constituting the tube bodyportion, and the tops of the beads are brazed to the inner surface ofthe tube body portion.

The invention recited in claim 42 of the present application is the heatexchanger tube according to any one of claims 39 through 41, wherein thebrazing material disposed within the flow passages has a melting pointlower than that of the brazing material which melts from the otherconstituting members and penetrates into the flow passages.

The invention recited in claim 43 of the present application is the heatexchanger tube according to any one of claims 39 through 41, wherein thebrazing material disposed within the flow passages melts earlier thanthe brazing material which melts from the other constituting members andpenetrates into the flow passages because the tube has a thermalresistance which is lower than that of the other constituting members.

The invention recited in claim 44 of the present application is the heatexchanger tube according to any one of claims 39 through 43, wherein theflow passages divided by the flow passage dividing body have anequivalent diameter of 0.559 mm or less.

The invention recited in claim 45 of the present application is the heatexchanger tube according to claim 44, wherein the flow passages dividedby the flow passage dividing body have an equivalent diameter of 0.254mm to 0.559 mm.

The invention recited in claim 46 of the present application is the heatexchanger tube according to any one of claims 39 through 45, whereinamong plural flow passages divided by the flow passage dividing body, anequivalent diameter of the flow passages, which is positioned at thelowest position when brazing in the furnace, or individual equivalentdiameters of the flow passage positioned at the lowest position and flowpassages positioned near by when brazing in the furnace are larger thana whole average of the equivalent diameters of the plural flow passagesdivided by the inner fins.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory diagram showing a heat exchanger according toan embodiment of the present invention (First embodiment).

FIG. 2 is an explanatory diagram and an enlarged view of an essentialportion showing sections of a heat-exchanger tube, before brazingthereof, according to the embodiment of the present invention (Firstembodiment).

FIG. 3 is an explanatory diagram showing a section of a second materialaccording to the embodiment of the present invention (First embodiment).

FIG. 4 is an enlarged diagram of an essential portion showing a sectionof a heat-exchanger tube, before brazing thereof, according to anembodiment of the present invention (Second embodiment).

FIG. 5 is an enlarged diagram of an essential portion showing a sectionof a heat-exchanger tube, before brazing thereof, according to anembodiment of the present invention (Third embodiment).

FIG. 6 is an enlarged diagram of an essential portion showing a sectionof a heat-exchanger tube, before brazing thereof, according to theembodiment of the present invention (Third embodiment).

FIG. 7 is an enlarged diagram of an essential portion showing a sectionof a heat-exchanger tube, before brazing thereof, according to theembodiment of the present invention (Third embodiment).

FIG. 8 is an explanatory diagram showing a section of a heat-exchangertube, before brazing thereof, according to an embodiment of the presentinvention (Fourth embodiment).

BEST MODE FOR CARRYING OUT THE INVENTION

A first embodiment of the invention will be described below withreference to FIG. 1 through FIG. 3.

A heat exchanger 1 shown in FIG. 1 is a radiator for a refrigeratingcycle for in-car air conditioning mounted on an automobile. This heatexchanger 1 comprises a core 10 which is formed by alternately stackingheat exchanger tubes 100 and radiating fins 20, and a pair of tanks 30with which both ends of the individual heat exchanger tubes 100 in theirlongitudinal direction are in communicative connection.

Reinforcing members 40 each is disposed on upper and lower sides of thecore 10, and both ends of the individual reinforcing members 40 in theirlongitudinal direction are supported by the tanks 30.

An inlet 31 and an outlet 32 for a medium (namely, a refrigerant whichcirculates through the refrigerating cycle) are disposed at the requiredportions of the tanks 30, so that the medium which has entered throughthe inlet 31 flows through the heat exchanger tubes 100 while performingheat exchange with heat conducted to the core 10 and flows out throughthe outlet 32.

Constituting members of the heat exchanger 1, such as the fins 20, thetanks 30, the inlet 31, the outlet 32, the side plates 40 and the heatexchanger tubes 100 are formed of an aluminum or aluminum alloy member.They are assembled into one body by means of a jig, and the assembledbody undergoes a heat treatment in a furnace to be brazed into one body.To braze in the furnace, a brazing material and flux are disposed on therequired portions of the individual members.

The heat exchanger tube 100 of this embodiment shown in FIG. 2 has atube body portion 200 which forms the outer shell of flow passages 101for flowing the medium and corrugated inner fins 300 for dividing theflow passages 101 and the tops of the inner fins 300 are flat and brazedto the inner surface of the tube body portion 200.

This heat exchanger tube 100 has a thickness t_(tube) of 1.2 mm or less.It is desirable that the heat exchanger tube 100 has a thicknesst_(tube) of 0.8 to 1.2 mm. And, the heat exchanger tube 100 has a widthw_(tube) of 16 mm or less. It is desirable that the heat exchanger tube100 has a width w_(tube) of 12 to 16 mm. Besides, the individual flowpassages 101 divided by the inner fins 200 each having an equivalentdiameter of 0.559 mm or less. It is desirable that the flow passage 101has an equivalent diameter of 0.254 mm to 0.559 mm.

An equation to obtain the equivalent diameter de is de=4×(flow passagesectional area)/(overall length of wet edge of flow passage crosssection). The medium performs heat exchange with heat conducted to theheat exchanger tubes 100.

The tube body portion 200 is formed by roll forming a first material ofan aluminum or aluminum alloy strip. Both ends 201 of the first materialin its breadth direction are mutually engaged and brazed at one end 102of the heat exchanger tube 100 in its breadth direction so that they arenot separated from each other. And, the other end 103 of the heatexchanger tube 100 in its breadth direction is a portion wheresubstantially a center of the first material is bent.

The inner fins 300 are formed by roll forming a second material of analuminum or aluminum alloy strip. Pitch P between the tops of the innerfins is 1.0 mm or less. The inner fins 300 are inserted between thefirst materials in an appropriate stage of the roll forming of the tubebody portion 200 and disposed within the tube body portion 200.

In this embodiment, the brazing material, which is required for brazingthe tops 310 of the inner fins 300, which are a flow passage dividingbody to the inner surface of the tube body portion 200, is not clad tothe first material which forms the tube body portion 200 but to thesecond material which forms the inner fins 300.

Specifically, in a case where the tops 310 of the inner fins 300 and theinner surface of the tube body portion 200 are brazed, at least one ofthe first material and the second material is clad with the brazingmaterial, and the structure of cladding only the second material withthe brazing material is adopted in this embodiment. The reason for thisis to suppress the use of brazing material to a minimum requiredquantity. Its concept will be described below.

First, the brazing material containing silicon is indispensable forbrazing but becomes a cause of eroding the core material after brazing.Therefore, it is desirable that the brazing material is suppressed to aquantity as small as possible. And, a material clad with the brazingmaterial is produced by stacking and rolling the core material and thebrazing material at a prescribed ratio, so that the thickness of theclad layer of the brazing material has a lower limit with respect to thethickness of the material. According to the present technology, thelower limit of the thickness of the clad layer is about 5% with respectto the thickness of the material.

Besides, where thickness t₁ of the first material and thickness t₂ ofthe second material are compared, the thickness t₂ of the secondmaterial can be made thinner to some extent in view of the structure ofthe heat exchanger tube 100. As a result, only the second material isdesirably clad with the brazing material to determine the brazingmaterial to a small quantity.

Meanwhile, the ends 201 of the first material are brazed with thebrazing material, which penetrates from the tanks 30 by capillaryaction, by brazing in the furnace described above. According to thisconfiguration, the quantity of the brazing material to be used can bereduced, and the depth of a silicon diffusion layer of the firstmaterial can be decreased, so that the thickness of the first materialcan be made thinner.

For improvement of support strength of the inner fins 300 to the tubebody portion 200 and durability of the inner fins 300, the ends 301 ofthe second material in its breadth direction are brazed to the firstmaterial with the brazing material which is clad to the second material.Brazing of the ends 301 of the second material to the first materialprevents the ends 301 of the second material from being fluctuated bythe flowing medium, and the durability of the heat exchanger tubes 100and the stability of the medium flow can be improved surely.

The thickness t₁ of the first material is 0.25 mm or less. It isdesirable that the thickness t₁ of the first material is 0.18 to 0.24mm. And, an Al—Zn alloy layer is disposed as a sacrifice layer forimproving corrosion resistance of the heat exchanger tubes 100 on thesurface of the first material which becomes the outer shell of the heatexchanger tube 100.

Meanwhile, the second material is formed by disposing a clad layer 300 bof the brazing material on both surfaces of a core material 300 a asshown in FIG. 3, and its thickness t₂ is 0.1 mm or less. It is desirablethat the thickness t₂ of the second material is 0.05 to 0.07 mm. And,the thickness of the clad layer 300 b of the brazing material in thesecond material is 5 to 10% in ratio with respect to the thickness t₂ ofthe second material.

In this embodiment, the tops 310 of the inner fins 300 are flat, so thatsufficient brazing areas are secured between the tops 310 of the innerfins 300 and the inner surface of the tube body portion 200.

In other words, brazing strength and reliability of brazing are improvedsurely by configuring as described above. And, friction between the tubebody portion 200 and the inner fins 300 is increased because the tops310 of the inner fins 300 are flat. Thus, there is also an advantagethat when the heat exchanger tube 100 is cut to a prescribed lengthbefore brazing, displacement of the inner fins 300 can be prevented.Width W_(flat) of the flat portions of the tops 310 is 2.5 to 0.5 whenthe thickness t₂ of the material is 1.

Besides, a portion between the tops 310 and 310 of the inner fins 300becomes non-perpendicular to a central axis L of the heat exchanger tube100 in its breadth direction. Specifically, an intersection angle θbetween the portion between the tops 310 and 310 of the inner fins 300and the central axis L in the breadth direction is 65 to 85°. In a casewhere the intersection angle θ is perpendicular and the heat exchangertubes 100 is cut to a prescribed length before brazing, the inner fins300 are largely deformed when a cutting blade is moved in parallel tothe central axis L in the breadth direction. But, such a disadvantage isavoided in this embodiment by setting the intersection angle θ to afavorable value.

In this embodiment, where the brazing is effected in the furnace, thebrazing material which is clad to the second material melts earlier thanthe brazing material, which melts from the other constituting memberssuch as the tanks 30 constituting the heat exchanger 1 and penetratesinto the flow passages 101, thereby to prevent the flow passages 101from being clogged. If the interior of the heat exchanger tube 100 isdry when the brazing material penetrates into the flow passages 101 fromoutside, the penetrated brazing material stays locally within the flowpassages 101 because of an influence of its surface tension and thelike, and the flow passages 101 are clogged. The brazing material whichis clad to the second material has a melting point lower than that ofthe brazing material which melts from the surfaces of the tanks 30 andpenetrates into the flow passages 101. Otherwise, the brazing materialwhich is clad to the second material melts earlier than the brazingmaterial which melts from the surface of the tanks 30 and penetratesinto the flow passages 101 because a thermal resistance of the heatexchanger tubes 100 is smaller than that of the tanks 30.

Besides, to prevent the flow passages 101 from being clogged, among theplural flow passages 101 divided by the inner fins 300, the equivalentdiameter of the flow passage 101, which is positioned at the lowestposition when brazing in the furnace, or the individual equivalentdiameters of the flow passage 101 which is positioned at the lowestposition and the flow passages 101 which are positioned nearby whenbrazing in the furnace are desirably determined to be larger than awhole average of the equivalent diameters of the plural flow passages101 which are divided by the inner fins 300.

It is because the melted brazing material tends to move in a directionof gravitational force, so that the flow passage 101 which is positionedat the lowest position when brazing in the furnace and the flow passages101 which are positioned nearby tend to have a large amount of thepenetrated brazing material in comparison with the other flow passages101.

In this embodiment, the heat exchanger 1 is brazed in the furnace withthe core 10 laid on its side, so that the equivalent diameter of theflow passage 101 which is positioned at one end 102 of the heatexchanger tube 100 in its breadth direction is determined larger, and ifnecessary, the equivalent diameter of the flow passage 101 positionednear the pertinent flow passage 101 is also determined to be large.Otherwise, the equivalent diameter of the flow passage 101 which ispositioned at the other end 103 of the heat exchanger tube 100 in itsbreadth direction is determined to be large, and if necessary, theequivalent diameter of the flow passage 101 which is positioned near thepertinent flow passage 101 is also determined to be large.

Where the equivalent diameter of the flow passage 101 which ispositioned near the flow passage 101 which is positioned at one end 102or the other end 103 is determined to be large, a pitch P of the tops atthe required portions of the inner fins 300 is determined to be largerthan a pitch P of the tops at the other portion.

Besides, when the equivalent diameter of the flow passage 101 at the oneend 102 and the equivalent diameter of the flow passage 101 at the otherend 103 are determined to be large, either end may be positioned on thelower side, so that it is also possible to secure generality in terms ofbrazing posture.

As described above, the heat exchanger tube 100 of this embodiment isconfigured very rationally and can be used favorably as a component partof the heat exchanger 1. Setting of the values of the individualportions of the heat exchanger tubes 100 was obtained by studying theperformance of the heat exchanger tubes 100 based on the currentmanufacturing technology.

It should be noted that the structure of this embodiment can be changedin its design appropriately without departing from the technical scoperecited in the appended claims and is not limited to the illustratedone.

Then, a second embodiment of the invention will be described withreference to FIG. 4.

As shown in FIG. 4, the heat exchanger tube 100 of this embodiment hasboth ends 201 of the first material in its breadth direction mutuallyengaged and brazed at one end 102 of the heat exchanger tube 100 in itsbreadth direction so that they are not separated from each other. And,the other end 301 of the second material is brazed with the end 201 ofthe first material. The other basic structure is same with that of theabove-described embodiment.

Thus, the end 301 of the second material may be brazed to the end 201 ofthe first material.

A third embodiment of the present invention will be described withreference to FIG. 5 through FIG. 7.

As shown in FIG. 5, the heat exchanger tube 100 of this embodiment hasboth ends 201 of the first material in its breadth direction mutuallyengaged and brazed at one end 102 of the heat exchanger tube 100 in itsbreadth direction with the end 301 of the second material in its breadthdirection sandwiched so that they are not separated from each other.

The end 201 of the first material and the end 301 of the second materialare brazed with the brazing material which is clad to the secondmaterial and the brazing material which penetrates from the tanks 30.

A shape of the end 201 of the first material and a shape of the end 301of the second material can be determined appropriately as shown in, forexample, FIG. 6 and FIG. 7, and are not limited to a particular shape.The other basic structure is same with that of the above-describedembodiment.

Thus, the end 301 of the second material may be configured to sandwichthe end 201 of the first material. According to this embodiment, theends 201 of the first material can be mutually brazed with the brazingmaterial which is clad to the second material. In a case where the ends201 of the first material in its breadth direction are mutually brazedwith only the brazing material which penetrates from the tanks 30, thereis a case that the brazing material does not spread sufficiently if theheat exchanger tube 100 is relatively long, and defective brazing may becaused. In this connection, such a defect can be avoided by thisembodiment, and the brazing of the ends 201 of the first material in itsbreadth direction can be improved surely in its reliability.

And, the end 301 of the second material in its breadth direction issandwiched between both ends 201 of the first material in its breadthdirection, so that the inner fins 300 can be positioned accuratelywithin the heat exchanger tube 100. Especially, the size of the flowpassage 101 at one end 102 and the other end 103 of the heat exchangertube 100 can also be controlled accurately. And, a decrease inresistance to pressure due to displacement of the inner fins 300 canalso be prevented.

Then, a fourth embodiment of the present invention will be describedwith reference to FIG. 8.

As shown in FIG. 8, in the heat exchanger tube 100 of this embodiment,beads 202 which are formed by shaping the required portions of the firstmaterial are disposed as a flow passage dividing body for dividing theflow passages 101. The tops of the beads 202 are brazed to the innersurface of tube body portion 200.

The brazing material which is required for brazing the tube body portion200 with the tops of the beads 202, and the brazing material which isrequired for brazing the both ends 201 of the first material, are cladto one surface of the first material which becomes the inside of theflow passages. When brazing in the furnace, the brazing material whichis clad to the first material melts earlier than the brazing materialwhich penetrates from outside into the flow passages 101, so that theflow passages 101 are prevented from being clogged. And the other basicstructure is same with that of the above-described embodiment.

Thus, the beads can also be disposed as the flow passage dividing body.In such a case, the brazing material is clad to the first material, andto braze in the furnace, it is configured so that the brazing materialmelts earlier than the brazing material, which melts from the otherconstituting members constituting the heat exchanger, and penetratesinto the flow passages 101.

INDUSTRIAL APPLICABILITY

The heat exchanger tubes of the present invention can be used asconstituting members of, for example, a vehicle-mounted heat exchanger.

1. A heat exchanger tube comprising: a tube body portion constituting anouter shell of flow passages for flowing a medium, and corrugated innerfins for dividing the flow passages, the tops of the inner fins are flattubes brazed to the inner surface of the tube body portion and in whichthe medium performs heat exchange with heat conducted to the tube,wherein: a brazing material which is required for brazing the tops ofthe inner fins and the inner surface of the tube body portion is notclad to a first material constituting the tube body portion but clad toa second material constituting the inner fins.
 2. The heat exchangertube according to claim 1, wherein a thickness of a clad layer of thebrazing material in the second material is 5 to 10% in ratio withrespect to the thickness of the second material.
 3. The heat exchangertube according to claim 1, wherein the second material has a thicknessof 0.1 mm or less.
 4. The heat exchanger tube according to claim 3,wherein the second material has a thickness of 0.05 to 0.07 mm.
 5. Theheat exchanger tube according to claim 1, wherein the first material hasa thickness of 0.25 mm or less.
 6. The heat exchanger tube according toclaim 5, wherein the first material has a thickness of 0.18 to 0.24 mm.7. The heat exchanger tube according to claim 1, wherein the tube has athickness of 1.2 mm or less.
 8. The heat exchanger tube according toclaim 7, wherein the tube has a thickness of 0.8 to 1.2 mm.
 9. The heatexchanger tube according to claim 1, wherein the tube has a width of 16mm or less.
 10. The heat exchanger tube according to claim 9, whereinthe tube has a width of 12 to 16 mm.
 11. The heat exchanger tubeaccording to claim 1, wherein the flow passages divided by the innerfins have an equivalent diameter of 0.559 mm or less.
 12. The heatexchanger tube according to claim 11, wherein the flow passages dividedby the inner fins have an equivalent diameter of 0.254 mm to 0.559 mm.13. The heat exchanger tube according to claim 1, wherein the tops ofthe inner fins have a pitch of 1.0 mm or less.
 14. The heat exchangertube according to claim 1, wherein an Al—Zn alloy layer is formed on thesurface of the first material which becomes an outer shell of the tube.15. The heat exchanger tube according to claim 1, wherein the tops ofthe inner fins are flat.
 16. The heat exchanger tube according to claim1, wherein ends of the second material in its breadth direction arebrazed with the first material by the brazing material which is clad tothe second material.
 17. The heat exchanger tube according to claim 16,wherein both ends of the first material in its breadth direction areengaged and brazed with an end of the second material in its breadthdirection sandwiched at one end of the tube in its breadth direction soas not to separate from each other.
 18. The heat exchanger tubeaccording to claim 1, wherein the portion between the tops of the innerfins is not perpendicular with respect to the central axis of the tubein its breadth direction.
 19. The heat exchanger tube according to claim1, wherein: the tube is a constituting member of the heat exchanger, andthe heat exchanger is produced by assembling the tube and otherconstituting members into one body and brazing the assembled body in afurnace, and the brazing material clad to the second material melts whenbrazed in the furnace earlier than the brazing material which melts fromthe other constituting members and penetrates into the flow passages toprevent the flow passages from being clogged.
 20. The heat exchangertube according to claim 19, wherein the brazing material clad to thesecond material has a melting point lower than that of the brazingmaterial which melts from the other constituting members and penetratesinto the flow passages.
 21. The heat exchanger tube according to claim19, wherein the brazing material clad to the second material meltsearlier than the brazing material which melts from the otherconstituting members and penetrates into the flow passages because thetube has a thermal resistance lower than that of the other constitutingmembers.
 22. The heat exchanger tube according to claim 1, wherein amongplural flow passages divided by the inner fins, an equivalent diameterof the flow passage, which is positioned at the lowest position whenbrazing in the furnace, or individual equivalent diameters of the flowpassages positioned at the lowest position and flow passages positionednearby when brazing in the furnace are larger than a whole average ofthe equivalent diameters of the plural flow passages divided by theinner fins.
 23. A heat exchanger tube comprising: a tube body portionconstituting an outer shell of flow passages for flowing a medium, andcorrugated inner fins for dividing the flow passages, the tops of theinner fins are flat tube brazed to the inner surface of the tube bodyportion and in which the medium performs heat exchange with heatconducted to the tube, wherein: the tube has a thickness of 1.2 mm orless, the tube has a width of 16 mm or less, the first materialconstituting the tube body portion has a thickness of 0.25 mm or less,the second material constituting the inner fins has a thickness of 0.10mm or less, and the flow passages divided by the inner fins have anequivalent diameter of 0.559 mm or less.
 24. The heat exchanger tubeaccording to claim 23, wherein the second material has a thickness of0.05 to 0.07 mm.
 25. The heat exchanger tube according to claim 23,wherein the first material has a thickness of 0.18 to 0.24 mm.
 26. Theheat exchanger tube according to claim 23, wherein the tube has athickness of 0.8 to 1.2 mm.
 27. The heat exchanger tube according toclaim 23, wherein the tube has a width of 12 to 16 mm.
 28. The heatexchanger tube according to claim 23, wherein the flow passages dividedby the inner fins have an equivalent diameter of 0.254 mm to 0.559 mm.29. The heat exchanger tube according to claim 23, wherein the tops ofthe inner fins have a pitch of 1.0 mm or less.
 30. The heat exchangertube according to claim 23, wherein an Al—Zn alloy layer is formed onthe surface of the first material which becomes an outer shell of thetube.
 31. The heat exchanger tube according to claim 23, wherein thetops of the inner fins are flat.
 32. The heat exchanger tube accordingto claim 23, wherein ends of the second material in its breadthdirection are brazed to the first material.
 33. The heat exchanger tubeaccording to claim 32, wherein both ends of the first material in itsbreadth direction are engaged and brazed with an end of the secondmaterial in its breadth direction sandwiched at one end of the tube inits breadth direction so as not to separate from each other.
 34. Theheat exchanger tube according to claim 23, wherein the portion betweenthe tops of the inner fins is not perpendicular with respect to thecentral axis of the tube in its breadth direction.
 35. The heatexchanger tube according to claim 23, wherein: the tube is aconstituting member of the heat exchanger, and the heat exchanger isproduced by assembling the tube and other constituting members into onebody and brazing the assembled body in a furnace, the brazing materialwhich is required for brazing the tops of the inner fins and the innersurface of the tube body portion is disposed within the flow passages,and the brazing material disposed within the flow passages melts whenbrazed in the furnace earlier than the brazing material which melts fromthe other constituting members and penetrates into the flow passages toprevent the flow passages from being clogged.
 36. The heat exchangertube according to claim 35, wherein the brazing material disposed withinthe flow passages has a melting point lower than that of the brazingmaterial which melts from the other constituting members and penetratesinto the flow passages.
 37. The heat exchanger tube according to claim35, wherein the brazing material disposed within the flow passages meltsearlier than the brazing material which melts from the otherconstituting members and penetrates into the flow passages because thetube has a thermal resistance which is lower than that of the otherconstituting members.
 38. The heat exchanger tube according to claim 35,wherein among plural flow passages divided by the inner fins, anequivalent diameter of the flow passage, which is positioned at thelowest position when brazing in the furnace, or individual equivalentdiameters of the flow passages positioned at the lowest position andflow passages positioned nearby when brazing in the furnace are largerthan a whole average of the equivalent diameters of the plural flowpassages divided by the inner fins.
 39. A heat exchanger tubecomprising: a tube body portion constituting an outer shell of flowpassages for flowing a medium, and a flow passage dividing body fordividing the flow passages, the flow passage dividing body being a tubebrazed to the inner surface of the tube body portion, and the mediumperforming heat exchange with heat conducted to the tube, wherein: thetube is a constituting member of a heat exchanger, and the heatexchanger is produced by assembling the tube and other constitutingmembers into one body and brazing the assembled body in a furnace, abrazing material which is required for brazing the flow passage dividingbody and the inner surface of the tube body portion is disposed withinthe flow passages, and the brazing material disposed within the flowpassages melts when brazed in the furnace earlier than the brazingmaterial which melts from the other constituting members and penetratesinto the flow passages to prevent the flow passages from being clogged.40. The heat exchanger tube according to claim 39, wherein the flowpassage dividing body is corrugated inner fins, and the tops of theinner fins are brazed to the inner surface of the tube body portion. 41.The heat exchanger tube according to claim 39, wherein the flow passagedividing body is beads obtained by shaping a material constituting thetube body portion, and the tops of the beads are brazed to the innersurface of the tube body portion.
 42. The heat exchanger tube accordingto claim 39, wherein the brazing material disposed within the flowpassages has a melting point lower than that of the brazing materialwhich melts from the other constituting members and penetrates into theflow passages.
 43. The heat exchanger tube according to claim 39,wherein the brazing material disposed within the flow passages meltsearlier than the brazing material which melts from the otherconstituting members and penetrates into the flow passages because thetube has a thermal resistance which is lower than that of the othercomponent members.
 44. The heat exchanger tube according to claim 39,wherein the flow passages divided by the flow passage dividing body havean equivalent diameter of 0.559 mm or less.
 45. The heat exchanger tubeaccording to claim 44, wherein the flow passages divided by the flowpassage dividing body have an equivalent diameter of 0.254 mm to 0.559mm.
 46. The heat exchanger tube according to claim 39, wherein amongplural flow passages divided by the flow passage dividing body, anequivalent diameter of the flow passages, which are positioned at thelowest position when brazing in the furnace, or individual equivalentdiameters of the flow passages positioned at the lowest position andflow passages positioned nearby when brazing in the furnace are largerthan a whole average of the equivalent diameters of the plural flowpassages divided by the inner fins.